Taxonomy and distribution of freshwater Hildebrandia Nardo (Hildenbrandial Rhodophyta) in central Mexico

Abstract

This work includes a taxonomic analysis, habitat descriptions and distribution of 23 populations of the genus Hildenbrandia, collected in 14 sities in Mexico and one in Central Europe. Twenty two populations from Mexico were considered as belonging to a sigle species (H. angolensis), characterized by having small cell diameter (mean 4.1 µm). The second species (H. rivularis), represented by 1 population from central Europe was characterized by the large cell diameter (mean 6.4 µm). The presence of propagules was observed in 10 Mexican populations. Hildenbrandia angolensis tended to occur in warm (temperature 23-27 ºC), neutral to alkalline (pH 7.0-8.0), high ion content (specific conductance (700-1520 µS cm^-1), moderate to fast flowing, high alkalinity (400-554 mg l^-1) and shallow waters (depth typically <70 cm); these data are essntially similar to previous records. Hildenbrandia angolensis is described for the first time from the higher Balsas and lower Papaloapan basins, both ocurring mostly in areas of tropical or subtropical rainforests.